1. Field of the Invention
The present invention relates to a display apparatus used in a compact calculator or the like with a fraction calculating function.
2. Description of Prior Art
Conventionally, electronic calculators capable of performing fraction calculation have been widely available in the market.
FIG. 8 shows a typical display unit of the conventional calculator having the fraction calculating function. As represented in FIG. 8, a plurality of 8-shaped display elements constructed of 7 segments per 1 digit are arranged along the horizontal (line) direction.
In such a conventional display unit, since numerals are displayed along this line direction, a fraction is displayed in a specific form different from the normal fraction display form.
FIG. 9 represents a display state of a mixed fraction (e.g., 12/3, namely one and two-third) displayed by the conventional display apparatus. In this case, the mixed fraction of one and two-third is displayed in such a specific display form that the respective numerical characters are arranged among reverse-L-shaped fraction symbols in the order of an integer, a numerator, and a denominator from the upper digit to the lower digit.
However, these conventional fraction display apparatus own the various problems. That is, a fraction formula is displayed in such a manner that the fraction symbols are arranged among the integer, numerator, and denominator of this fraction formula. Such a specific fraction display form is completely different from the normal, or General mathmatical expression form. As a result, any users who do not master such a specific fraction display form may be confused by this fraction display. Furthermore, a total number of display digit occupied by this fraction formula becomes large, as compared with the normal formula such as an integer. In the worst case, a fraction formula with a large numeral value (namely, large digit) cannot be displayed on the display apparatus, i.e., over flow.
On the other hand, the conventional compact electric calculators having the fraction entry function are equipped with the fraction enter key, for instance, "a.b/c". Then, a fraction formula is entered by operating a combination with the number entry key and the fraction entry key.
For example, when a mixed fraction of "a.b/c" is entered by the conventional compact electric calculator with the fraction entry function, the key operation is carried out in such a way that the numeric value indicative of the integer "a" is first entered, the fraction entry key "a.b/c" is manipulated, the numeric value representative of the numerator "b", and subsequently, the fraction entry key "a.b/c" is manipulated, and finally, the numeral value of the denominator "C" is entered.
However, the Japanese typical reading way of the mixed fraction "23/4" is "two and fourth-three". In other words, this mixed fraction is read in the order of the integer "2", the denominator "4", and the numerator "3". As a consequence, there is a difference in the fraction entry key operation order for the conventional calculator with respect to the reading way of this mixed fraction, which may induce misoperation of the fraction formula entry.